I personally think it's hard to compare these phones in terms of which one is better than the other - I don't think this necessarily boils down to just specs; but also to subjectivity and personal preference, as well as to what you're looking for in a phone. The LG G6 came out much earlier than the Note 8; so Snapdragon on the 8 is newer. And, if you like phones that are more phablet-oriented in size, then the Note 8 (though the G6 is 5.7", or close to that, from what I recall, is still pretty big) would be a better option.
Personally, I prefer the G6: it's more "handy" for me (I have small hands and so its screen-to-body ratio works perfectly for me); I enjoy LG's software; and I prefer the phone's aesthetics. I've never been a huge fan of Samsung, but I definitely respect them for their customer service and for putting out quality devices.